The present invention relates to an apparatus and method for the application of water and liquid chemicals to agricultural fields. More particularly this invention relates to an irrigation system, effective in low energy precision application techniques, which utilizes a programmable controller for the application of precise amounts of liquid chemicals and water.
New chemicals such as growth regulators, anti-transpirants and soil surface evaporation suppressants are being developed which may open new horizons in water conservation. However, the success of these chemicals in agricultural applications may depend upon the ability of the agriculturalist to make timely and accurate application of these chemicals in precise amounts at particular locations on the plant. In particular, new methods such as low energy precision application (LEPA) irrigation and low or no-till methods offer a number of advantages such as decreased energy consumption, decreased water usage and increased chemical efficiency over more conventional methods. In addition, the effectiveness of many chemicals currently being used in more conventional agricultural production may be increased by application by a system capable of precise, accurate application.
Current methods for the application of agricultural chemicals include aerial, ground and chemigation methods. These methods are, for the most part, incapable of the precise application of water and liquid chemicals necessary for LEPA methods in that they suffer from one or more of the following defects or limitations.
Application of chemicals with tractor-driven sprayers suffers from many of such defects. For instance, such application techniques are often limited by and untimely due to wet soil from irrigation or rainfall. Further, the necessity for driving a tractor through the field often results in foilage damage to the crop and unnecessary soil compaction in the wheel tracks.
Aerial application is particularly subject to many factors which may adversely affect coverage. These factors include dense crop canopies, high winds, atmospheric inversion layers, and poor regulation of the amount of liquid applied. Research has shown that a very low percentage of aerially-applied chemicals penetrate the canopies of some crops, and therefore these chemicals fail to reach the area of insect infestation. Aerial application is simply incapable of the precision of application required by LEPA methods.
Chemigation, the application of chemicals simultaneously while irrigating, has been accomplished with both surface and sprinkler systems. However, surface methods are limited to soil applied chemicals and the distribution uniformity which may be very low under certain circumstances, is no better for the chemical than that of the water which is applied. Chemicals that are injected directly into the irrigation water and applied through sprinkler systems are subject to the non-uniformity of the water application. This non-uniformity may be quite drastic in high wind conditions. Other problems in sprinkler-applied chemicals stem from the fact that a single nozzle, located above the crop canopy, is used to apply both soil-active chemicals and foliage-applied materials. The result is that the effectiveness of foliage-applied chemicals is decreased due to the washing by excess water which is simultaneously applied. Likewise, some soil applied chemicals are intercepted by leaves and are lost by volatilization.
These problems of non-uniformity and poor localization of the chemical being applied are compounded by the speed control and alignment of present electrically-driven irrigation systems. These systems use intermittent move-type systems controlled by a percent timer. For example, if a system is to move at 20% of its maximum speed, the timer could move it for 12 seconds out of a minute, and the system would then remain stationary for the remaining 48 seconds. Because it is stationary for a length of time, this type of irrigation system results in additional uneven chemical distribution, with the resulting decrease in effectiveness described above. In particular, this type of system is ineffective for LEPA methods, which are particularly dependent upon the uniform application of precise amounts of water and chemicals at a precise location into microbasins or above the furrow or the crop canopy.